1. Field of the Invention
This invention relates to a composite material composed of a rapidly-quenched alloy matrix and particles of a second-phase substance dispersed therein.
2. Description of the Prior Art
The requirements for the properties and performance of metallic materials have recently become more stringent and versatile. A composite material is one of the possible solutions to these requirements. A typical composite material comprises a metal alloy phase and a second phase of particles dispersed therein. More specifically, Cu--C, Fe--BN, etc. are known as a material for making sliding parts, and WC--Co, WC--TiC--Co, etc. are known as ultrahard alloys. They are produced by powder metallurgy, and tend to be porous. There is a serious limitation to the shape of the material which can be produced by powder metallurgy. Powder metallurgy provides a uniform, three-dimensional dispersion of second-phase particles, but has the disadvantage of tending to create pores in the composite material. Although a composite material made by melting is substantially free from any such pore, the second-phase particles are not dispersed uniformly in the molten metal, but in many cases float towards its surface. The second phase is separated from the alloy phase, and the material cannot withstand a high mechanical stress. Various methods have been proposed to improve those problems, but none of them has been found capable of producing a composite material which is sufficiently strong against a mechanical stress.